I pulled my plugs today to see what color they were and I noticed that #1,2 and 4 were white while the others were black. My question is what could cause this? I recently adjusted my valves, it's got a new fuel pump, plugs etc. Timing is set around 8 degrees or so and the carbs are balanced. She idles nice at 800 rpms, and I'm running an e12-80 out of a ZX with an alt. conversion for more juice. I could understand that 1&2 could be slightly lean because they both feed off the same runner, but #4 has it's own and it's lean, I'm stumped. Any ideas out there?? Thanks

colortune your carbs, check your spark plug gaps and your cylinder compression

I've tried the colortune before and it showed all were running rich(yellow), couldn't really get them to reach blue so I tuned it by ear. The compression is good, around 170 across all cylinders and the plugs are gapped at .35. It burns a little oil due to bad valve seals, but generally runs decent. Sometimes it feels like the car is starving a little under accleration, but other times it's fine. Wondering if more fuel volume from an elec pump would feed the carbs better under a load.

The lean cylinders and if they were 1,2 and 3 or 4,5 & 6 then you could suspect a mixture problem from one carb . Tossing in the odd cylinder changes my thinking on this . However have you checked the fuel level in the float bowl on the front carb ? Also there are screens installed in the inlet of the carbs that could be clogged . Remove them there not needed , one could be blocked . Taking a compression test is good advise especially if this started happening after you adjusted the valves . Too tight of adjustment could cause a lean showing , also burn valves . You have great compression at 170 and being they are all close as you say is even better . Gary

The fact that you are showing a rich mixture with a color tune even thou you are showing a lean condition. I don't understand . Also you asked about adding a electric fuel pump for more pressure . If your pump is making 3 to4 psi. that is plenty . Providing it can maintain some pressure at speed . You don't really need a lot of volume . Before adding a pump check all filters and supply lines .

I recently cleaned out all my hard lines, installed new fuel hoses, new filter, removed the screens, etc, basically cleaned the whole fuel system. Also I checked my compression after my valve adjustment. I'm curious about my valves possibly being out of adjustment. Maybe I got this backwards, but I'm thinking that if it's lean that the intake valve would be too loose(not openening enough to let in fuel). Wouldn't a tight valve mean that it never fully closes all the way. My fuel pump idea comes about because sometimes at highway speeds when I try to accelerate it feels like it's starving for fuel, this doesn't happen all the time though, and never causes it to stumble, just not as much power.